A Head Full of Ghosts

A Head Full of Ghosts is a 2015 horror novel by American writer Paul Tremblay. The plot involves a Massachusetts family under financial and emotional strain while their fourteen-year-old daughter, Marjorie Barrett, exhibits signs of severe mental illness. The Barretts come to believe she is possessed by a demon, and her behavior is publicized when the family stars in a reality TV show. Marjorie's younger sister, Merry Barrett, relays the experiences of her childhood fifteen years later. Themes include elements of Catholic exorcism and reality television exploitation.

Tremblay dedicated the novel to Shirley Jackson. A Head Full of Ghosts has been noted to have plot and thematic similarities to Jackson's We Have Always Lived In The Castle. Merry Barrett's name is also similar to that of Merricat Blackwood.

The novel was published on June 2, 2015 by William Morrow and won the Horror Writers Association's Bram Stoker Award for Novel in 2015. Focus Features has acquired the rights to develop a movie adaptation.